Detecting an imminent loss of control through sensor re-use
To detect aquaplaning
situations, video images from surround view cameras mounted in the side
mirrors, the grill, and rear are analyzed. “When there is a lot of water on the
road, the camera images show a specific splash and spray pattern that can be
detected as aquaplaning in its early phase”, explained Hartmann. For example,
excessive water displacement in all directions underneath the tyre is a
characteristic attribute. During the first testing phase of the new solution,
the wetness recognition algorithms delivered a very high hit ratio in
predicting potential aquaplaning conditions.
In addition to image
information, Continental uses information from tyres to detect the risk of
aquaplaning. In this concept, signals from Continental’s eTIS sensors, mounted
on the tire’s inner liner, are computed. “We use the accelerometer signal from
the electronic-Tire Information System to look for a specific signal pattern”,
said Andreas Wolf, head of Continental's Body & Security business unit. A
tire model processes the incoming radial acceleration of the part of the tire
that is in contact with the road. For wet roads – when enough water is
transported out of the tread to ensure an appropriate grip – the signal shows a
distinct pattern.
As soon as a wedge of water
begins to form in front of the tyre footprint region and there is excessive
water on the road, the acceleration signal begins to oscillate in a
characteristic way, indicating an early risk of aquaplaning. Since the eTIS
sensor can also detect the remaining depth of the tire tread, a safe speed for
a given wet road condition can be calculated and communicated to the driver.
Testing has shown that future
aquaplaning assistance will also have the potential to intervene in an actual
aquaplaning situation by applying the rear brakes in a controlled way to
establish a degree of “torque vectoring” in order to maintain vehicle
maneuverability within physical limits.
Contribution to Vision Zero
Not only is aquaplaning a
challenge to the driver, but it is also difficult to pin down how many city
road and highway accidents in wet road conditions are caused by floating front
wheels. “This is one of the last blank spots on the strategic map towards
greater road safety”, said Bernd Hartmann. But drivers must continue to
consider a general rule: adjusting their speed to wet roads and keeping an eye
on the tyre’s tread depth. Since aquaplaning depends on tread depth, the height
of the water on the road and speed, Continental recommends renewing summer tyres
with three millimeters of residual tread depth. Below this limit, the risk of
aquaplaning increases significantly.